1. Field of the Invention
The present invention relates to a heat exchanger and more particularly to a structure which may be utilized for the water cooling of oil, as for example, in connection with the cooling of oil in a torque converter for a motor vehicle.
2. Description of Prior Art
In a conventional heat exchanger of this kind such as exemplified in U.S. Pat. No. 2,752,128, a turbulator formed from a flat-metal-sheet is disposed in an annular passageway formed by an inner and outer concentric tube. The turbulator is characterized by longitudinally aligned groups of parallel slits defining staggered trapezoidally-shaped portions offset from the plane of the metal-sheet. The material between each pair of adjacent slits in a group is positioned at opposite sides of the plane of the metal-sheet to form the trapezoidally-shaped portions.
In another conventional heat exchanger of this kind such as exemplified in U.S. Pat. No. 3,083,662, a turbulizer has a base and a plurality of longitudinally spaced groups of substantially trapezoidally shaped corrugations extending in one direction from the plane of the base. These groups extend transversely of the flat stock during formation and radially from the base when the turbulizer is formed into a circular configuration. Each of groups includes a series of spaced corrugations and an alternate series of longitudinally offset corrugations.
In these conventional heat exchangers, the flow therethrough is retarded by the turbulator or the turbulizer to increase turbulence and enhance the efficiency of heat transfer. However, it has a disadvantage in that heat transfer is diminished because of the fact that a large laminar sublayer is formed behind a side portion of the trapezoidally shaped portion due to the side portion being transverse to a direction of the fluid flow. Because the laminar sublayer of the fluid is of relatively low velosity compared with the normal fluid flow, it offers a high resistance to heat transfer.